About 78 of the us population is served by some kind

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Unformatted text preview: ning) Cyanide sump pond, California Cyanide heap-leach mining for
gold presents special problems
in California and other western
States. http://www.dep.state.pa.us/dep/deputate/minres/bamr/amd/science_of_amd.htm;
http://www.epa.gov/region08/superfund/sites/co/svlpondpic.html 72 Municipal Water Pollution
Cities produce an enormous variety
of water pollutants
– Street runoff
– Salts, fertilizers, heavy metals, biocides
– Sewage
• Three kinds of sewage treatment
– Primary (settling & skimming)
– Secondary (aerobic decomposition)
– Tertiary (chemical & biological purification) • About 78% of the US population is served by
some kind of municipal wastewater
treatment facility
Sources: Statistical Abstract of the US, 2000; http://www.csc.noaa.gov/rvat/environ.html;
http://css.snre.umich.edu/css_doc/CSS04-14.pdf 12 73 Agricultural Water Pollution 74 Biological Oxygen Demand
When too great a quantity
of plant nutrients get into
the water, they can set off
a series of steps that
result in the biological
death of a water body.
Steps to oxygen depletion Agriculture is the leading source of
non-point pollution in the US
There are 3 main types of agricultural
pollution
– FERTILIZERS
– BIOCIDES
• Herbicides
• Pesticides – ANIMAL WASTE –
–
–
– Feedlot, Roman L. Hruska U.S. Meat
Animal Research Center,
Clay Center, Nebraska Excess nutrients
Algal bloom and death
Bacterial decomposition
Oxygen depletion http://www.ars.usda.gov/is/AR/archive/oct98/odor1098.htm http://www.agnr.umd.edu/users/agron/nutrient/Factshee/Phosphorus/Eutrop.html 75 76 The Aral Sea: 1960s The Aral Sea: 1970s 1964 1973 http://edcwww.cr.usgs.gov/earthshots/slow/Aral/Aral http://edcwww.cr.usgs.gov/earthshots/slow/Aral/Aral 77 78 The Aral Sea: 1980s The Aral Sea: 1990s 1987 1999 http://edcwww.cr.usgs.gov/earthshots/slow/Aral/Aral http://edcwww.cr.usgs.gov/earthshots/slow/Aral/Aral 13 79 80 The Aral Sea: 2003 The Aral Sea Today
As recently as the 1980s 60,000 people were employed in the
Aral Sea fishing industry. Today, there is no commercial fishing
in the area.
Surface area is now less than 50% what it was in...
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